The present invention, generally, relates to sequential access media, more particularly, to provision of information about fragmentation of files on sequential access media.
A linear tape file system (LTFS) is software that allows for performing standard file operations to tape media and providing intuitive interface to users to manipulate files or directories on the tape media. Technical development of the LTFS format specification is now continued in SNIA (Storage Networking Industry Association) TWG (Technical Work Group).
Several implementations of the LTFS have been developed for tape drives and tape libraries. Hierarchical storage systems integrating with the LTFS, in which part of files is stored on tape media in the LTFS format, have been also developed.
Although the LTFS can present the tape media as disk like drives, the tape medium may not allow for random access since the tape medium is sequential in nature. Data for a signal file may be fragmented over the tape medium when partially updated data of the file is appended after other file, or the file is written together with other file. Since tape drives may take some time to locate start position of each fragment, read time for the fragmented file may prolong in comparison with a file recorded continuously on the tape medium, resulting in read performance degradation.
The read performance of such fragmented file can be improved by rewriting the file. However, degree of improvement by rewriting the file may depend on how the file is scattered over the tape medium. Regardless, there is lack of information about how the file is scattered over the tape medium as well as how much the read performance can be improved by rewriting the file. Standard application programming interfaces such as POSIX (Portable Operating System Interface) API do not provide any information about fragmentation of files and any suggestion about read performance improvement by rewriting.